Agilent InfinityLab LC Series RID User Manual
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4
Preparing the Module
Solvent Information
PEEK
PEEK (Polyether-Ether Ketones) combines excellent properties regarding
biocompatibility, chemical resistance, mechanical and thermal stability. PEEK is
therefore the material of choice for UHPLC and biochemical instrumentation.
It is stable in the specified pH range (for the Bio-inert LC system: pH 1 – 13, see
bio-inert module manuals for details), and inert to many common solvents.
There is still a number of known incompatibilities with chemicals such as
chloroform, methylene chloride, THF, DMSO, strong acids (nitric acid > 10 %,
sulfuric acid > 10 %, sulfonic acids, trichloroacetic acid), halogens or aqueous
halogen solutions, phenol and derivatives (cresols, salicylic acid, and so on).
When used above room temperature, PEEK is sensitive to bases and various
organic solvents, which can cause it to swell. Under such conditions, normal
PEEK capillaries are very sensitive to high pressure. Therefore, Agilent uses
stainless steel cladded PEEK capillaries in bio-inert systems. The use of stainless
steel cladded PEEK capillaries keeps the flow path free of steel and ensures
pressure stability to at least 600 bar. If in doubt, consult the available literature
about the chemical compatibility of PEEK.
Polyimide
Agilent uses semi-crystalline polyimide for rotor seals in valves and needle seats
in autosamplers. One supplier of polyimide is DuPont, which brands polyimide as
Vespel, which is also used by Agilent.
Polyimide is stable in a pH range between 1 and 10 and in most organic solvents.
It is incompatible with concentrated mineral acids (e.g. sulphuric acid), glacial
acetic acid, DMSO and THF. It is also degraded by nucleophilic substances like
ammonia (e.g. ammonium salts in basic conditions) or acetates.
Polyethylene (PE)
Agilent uses UHMW (ultra-high molecular weight)-PE/PTFE blends for yellow
piston and wash seals, which are used in 1290 Infinity pumps, 1290 Infinity II
pumps, the G7104C and for normal phase applications in 1260 Infinity pumps.
Polyethylene has a good stability for most common inorganic solvents including
acids and bases in a pH range of 1 to 12.5. It is compatible with many organic
solvents used in chromatographic systems like methanol, acetonitrile and
isopropanol. It has limited stability with aliphatic, aromatic and halogenated
hydrocarbons, THF, phenol and derivatives, concentrated acids and bases. For
normal phase applications, the maximum pressure should be limited to 200 bar.
